Genetic data from ancient Europeans are rewriting the prehistory of the continent

By Tina Hesman Saey, 11:30 AM May 1, 2014

Carles Lalueza-Fox nearly missed an opportunity to paint the genetic portrait of a 7,000-year-old Spaniard.

In 2006, spelunkers stumbled across the ancient remains of two men in a cave in Spain’s Cantabrian mountain range. Lalueza-Fox, an evolutionary geneticist at the Institute of Evolutionary Biology in Barcelona, got a call inviting him to examine the skeletons’ DNA.

“I told them I wasn’t interested,” he recalls. Most of the genetic material in the bones had probably long since crumbled into...